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From: "Emilio G. Cota" <cota@braap.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org,
	"Peter Crosthwaite" <crosthwaite.peter@gmail.com>,
	"Richard Henderson" <rth@twiddle.net>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	"Marcel Apfelbaum" <marcel.apfelbaum@gmail.com>,
	"Alex Bennée" <alex.bennee@linaro.org>
Subject: Re: [Qemu-devel] [PATCH 3/4] target/i386/translate: use thread-local storage in !user-mode
Date: Tue, 14 Aug 2018 03:34:12 -0400	[thread overview]
Message-ID: <20180814073412.GA32086@flamenco> (raw)
In-Reply-To: <5a55a78e-d4f2-2528-481c-9eda97718f81@redhat.com>

On Tue, Aug 14, 2018 at 08:31:02 +0200, Paolo Bonzini wrote:
> On 14/08/2018 03:38, Emilio G. Cota wrote:
> > Needed for MTTCG.
> > 
> > Signed-off-by: Emilio G. Cota <cota@braap.org>
> 
> Why not always use TLS, even in user-mode?

To avoid TLS waste; user-mode uses a single TCGContext,
so a single copy of these variables is all that's needed because
code generation is serialized with a lock.

If in user-mode we just have a few threads it'd be no big deal,
but apps can easily spawn thousands of threads.

		E.

  reply	other threads:[~2018-08-14  7:34 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-14  1:37 [Qemu-devel] [PATCH 0/4] x86_64 mttcg Emilio G. Cota
2018-08-14  1:37 ` [Qemu-devel] [PATCH 1/4] hw/i386/pc: hold the BQL when calling cpu_get_ticks Emilio G. Cota
2018-08-14  6:37   ` Paolo Bonzini
2018-08-14  1:37 ` [Qemu-devel] [PATCH 2/4] cpus: assert that the BQL is held in cpu_get_ticks Emilio G. Cota
2018-08-14  1:38 ` [Qemu-devel] [PATCH 3/4] target/i386/translate: use thread-local storage in !user-mode Emilio G. Cota
2018-08-14  6:31   ` Paolo Bonzini
2018-08-14  7:34     ` Emilio G. Cota [this message]
2018-08-14  1:38 ` [Qemu-devel] [PATCH 4/4] configure: enable mttcg for x86_64 Emilio G. Cota

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